AeroShell Diesel Ultra for general aviation aircraft piston engines.

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Mar 15, 2023
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I'm not sure which forum my questions fits best, but since (I think) AeroShell finishes their general aviation oils in the U.K., I picked this forum.

1. Does anyone know the rough base stock make-up of the AeroShell Diesel Ultra aviation oil for aviation diesel engines? %PAO, %AN?
2. If/when the oil is also used as a heat transfer medium (as is in most aviation piston engines via the oil squirts under the piston), which base stock (PAO or AN) makes the most sense? Is resistance to coking the biggest concern? Are there significant differences in the heat capacity of either base stock?

Thanks in advance for your comments.

Ref:

 
Don't know about their av oil but their aerobatic team is nonpareil.

aero shell.jpg
 
Are there many modern diesel powered aircraft that a special oil is made for them?
Quite a few. Diamond Aircraft has been using a couple of different versions of a Mercedes-derived I4 turbodiesel across most of its line for a while now.
 
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Many (compared to automobiles) may be a term that never applies to anything general aviation, where annual sales of piston engine aircraft have recently been between 1000 and 3000 aircraft. But there are some diesel powered models. The most common are the Diamond Aircraft, including the DA62 twin engine, the DA42 twin engine, the DA50RG single engine, the DA40NG single engine. I think about 200 of these aircraft were sold in 2022. So "many" doesn't exactly apply. However, more may be on the way, as the diesel engines in these production certified aircraft and other production and experimental aircraft are designed to burn Jet Fuel (kerosene), which is much more available worldwide that the current 100LL aviation gasoline.
 
PAO is used as a coolant for power supplies, military, aerospace, and industrial cooling applications, so it must be a good heat transfer fluid for the underside of pistons.
 
Fortunately, there is no exhaust treatment systems on aviation diesels. Unfortunately, these efficient engines are now becoming a target.
It’s only a matter of time. I’m not going to go political here but I’m caught in the middle of not wanting to endanger our troops lives with emissions equipped trucks but wanting our fearless leaders to experience the same issues that are forced on us. Military, Aerospace, Trains, Ships, they all need to be forced to meet the same standards as On/off highway equipment and I think things will start to change.
 
Fortunately, there is no exhaust treatment systems on aviation diesels. Unfortunately, these efficient engines are now becoming a target.
I'm not surprised, although I have to wonder, just how fast are things moving? I mean, avgas still contains lead, last I knew. I think EFI is making inroads?

I realize that getting certs for making changes is no minor task, neither is updating the fleet.

But I guess I could see, someone thinking, hey for anything new going forward, it needs to meet xyz regs. What's old is grandfathered, what's new, well, tough luck.
 
The only way to know the base oil composition is by the SDS, inside information, or gas chromatography (GC).

The SDS for this product shows 10 CAS #s for the base oils constituting 0-90%. These CAS #s represent petroleum distillates such as Group IIIs and hydrotreated naphthenics (not the same as AN), plus GTL and PAO. Any one or combination of these base oils may be present and ratios are not shown. The PAO content can only be determined by GC and if present is likely only what is needed for viscometrics. The SDS only shows ingredients considered hazardous, and other non-hazardous synthetic base oils may also be present, such as esters and ANs.

In other words it may or may not contain PAO, AN, or ester.

Product name : AeroShell Oil Diesel Ultra
SECTION 3. COMPOSITION/INFORMATION ON INGREDIENTS

Chemical nature : Synthetic base oil and additives.

Highly refined mineral oil. The highly refined mineral oil contains w) DMSOextract, according to IP346. The highly refined mineral oil is only present as additive diluent.

* contains one or more of the following CAS-numbers: 64742- 53-6, 64742-54-7, 64742-55-8, 64742-56-9, 64742-65-0, 68037-01-4, 72623-86-0, 72623-87-1, 8042-47-5, 848301-69- 9.

Hazardous components Chemical Name Synonyms CAS-No. Concentration (%)
Alkaryl amine 36878-20-3 1 - 3
Interchangeable low viscosity base oil (<20,5 cSt @40°C) * Not Assigned 0 - 90
 
I'm not surprised, although I have to wonder, just how fast are things moving? I mean, avgas still contains lead, last I knew. I think EFI is making inroads?

I realize that getting certs for making changes is no minor task, neither is updating the fleet.

But I guess I could see, someone thinking, hey for anything new going forward, it needs to meet xyz regs. What's old is grandfathered, what's new, well, tough luck.
Fuel injection is commonplace in new GA aircraft now. The leaded fuel is sailing into the sunset for sure, but currently the biggest issues are availability and price of unleaded 100.
 
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